 /*******************************************************************************
  * Copyright (c) 2004, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM - Initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.runtime.jobs;

 import org.eclipse.core.internal.jobs.JobManager;
 import org.eclipse.core.internal.jobs.LockManager;

 /**
  * A lock listener is notified whenever a thread is about to wait
  * on a lock, and when a thread is about to release a lock.
  * <p>
  * This class is for internal use by the platform-related plug-ins.
  * Clients outside of the base platform should not reference or subclass this class.
  * </p>
  *
  * @see IJobManager#setLockListener(LockListener)
  * @since 3.0
  */
 public class LockListener {
     private final LockManager manager = ((JobManager)Job.getJobManager()).getLockManager();

     /**
      * Notification that a thread is about to block on an attempt to acquire a lock.
      * Returns whether the thread should be granted immediate access to the lock.
      * <p>
      * This default implementation always returns <code>false</code>.
      * Subclasses may override.
      *
      * @param lockOwner the thread that currently owns the lock this thread is
      * waiting for, or <code>null</code> if unknown.
      * @return <code>true</code> if the thread should be granted immediate access,
      * and <code>false</code> if it should wait for the lock to be available
      */
     public boolean aboutToWait(Thread lockOwner) {
         return false;
     }

     /**
      * Notification that a thread is about to release a lock.
      * <p>
      * This default implementation does nothing. Subclasses may override.
      */
     public void aboutToRelease() {
         //do nothing
 }

     /**
      * Returns whether this thread currently owns any locks
      * @return <code>true</code> if this thread owns any locks, and
      * <code>false</code> otherwise.
      */
     protected final boolean isLockOwnerThread() {
         return manager.isLockOwner();
     }
 }

